In the past, various methods have been used to make foam cushions which provide both support as well as a soft, comfortable seat. The methods of preparing such cushions for the most part have involved the bonding together with adhesives of different types of foams and/or foams of different hardnesses to form a laminated cushion having the desired properties. Such methods are effective, but they are time consuming and relatively expensive.
In the Ahrens U.S. Pat. No. 4,190,697, a method is disclosed for producing a multidensity foam article suitable for use as a seat cushion without using adhesives. In the patented method, a foam cushion having a firm, high density foam bottom layer and a soft, low density foam top layer is prepared by placing a first formulation capable of yielding a firm foam into a mold, permitting said formulation to start rising and foaming, pouring a second liquid formulation capable of forming a soft foam through the rising first formulation so that the first formulation floats upon the second formulation, and then permitting the two formulations to foam, rise and cure into a multidensity foam article in which the foam layers of different density are bonded and knitted together at their common boundaries.